Primus leader Les Claypool says he got more than a little help from friends when the experimental rock trio recorded their sixth studio album.

The as-yet-untitled album, due in the fall, features a grab bag of musical confederates -- including a Northern California neighbor, streetwise singer/songwriter Tom Waits -- and members of hard-rocking groups Limp Bizkit, Rage Against the Machine and Metallica.

"We're thinking of these people as creative navigators," singer/bassist Claypool said of the album's numerous co-producers and special guests. "It will be more of a collaboration than some of our other albums."

The album will follow up the San Francisco Bay Area band's The Brown Album (1997), which featured "Bob's Party Time Lounge" (RealAudio excerpt).

Fred Durst, singer of Jacksonville, Fla., thrash-rockers Limp Bizkit, co-produced the song "Lacquer Head"; Rage guitarist Tom Morello joined Primus in a Los Angeles studio last month to produce and play on three tracks, including "Electric Uncle Sam" and "Mama Didn't Raise No Fool."

Ex-Police drummer Stewart Copeland also added his talents to the album: He produced "Dirty Drowning Man," which features vocals from Martina, the singer for trip-hop pioneer Tricky. Metallica guitarist Kirk Hammett and Mark Osegueda of the heavy-metal band Death Angel both appear on an untitled track, and Matt Stone, co-creator of the cartoon "South Park," produced "Natural Joe."

"It's sort of a mixed bag of tricks, as most Primus records are," Claypool said. "There's definitely sort of an acid-rock heaviness to it, but with that eclectic perspective. ... I listen to it and I go, 'Now wait a minute, this isn't really heavy metal, and it's not really like Korn, and it's not really funk, but it's got all these elements to it, and then there's this eerie, psychedelic perspective to it. ... It's like acid rock for the new millennium."

The 13 songs slated for the album are being mixed by Toby Wright (Alice in Chains, Korn). Meanwhile, the band -- Claypool, guitarist Larry LaLonde and drummer Brian "Brain" Mantia -- is on the road with the heavy-metal tour Ozzfest, which kicked off Thursday in West Palm Beach, Fla.

Primus fans at the Ozzfest shows will have a chance to preview three of the album's songs, courtesy of a two-and-a-half minute medley the band will distribute on cassette during the tour, according to Primus manager David Lefkowitz. The tape will include "Anti-Pop," which Claypool called the Primus flagship theme song, and "Eclectic Electric" -- described by Claypool as a nine-minute epic saga featuring guitarist Jim Martin, formerly of San Francisco rock band Faith No More.

Claypool said the most exciting aspect of the new album was the chance to work again with neighbor and friend Waits. The disheveled, gravel-voiced troubadour collaborated with Primus on the 1991 album Sailing the Seas of Cheese, providing the voice of "Tommy the Cat" on the song of the same name.

Primus returned the favor by backing up the singer on "Big in Japan" (RealAudio excerpt), a song from Waits' recently released Mule Variations.

Waits described the trio as "good guys and fearless adventurers. They love adventure. They will play anything; they will do anything. They like the unusual and the bizarre. They're game. They got zeal."

On the new album, Waits produced, played mellotron and sang on "Coattails of a Dead Man," another track with backing vocals from Martina.

"Producer is such an ambiguous word," Claypool said, "but I definitely think of Tom as one of those 'creative navigator' kind of people. We just approached all our big heroes, and [Waits] was definitely at the top of the list.

"Tom expresses himself with visuals," Claypool continued. "He'll listen to something and go, 'Ah, it sounds like the transaxle was blown out on old Willy's four-by-four.' He has this way of visualizing a song, and it just makes for interesting collaboration."

In his typically sardonic, metaphorical way, Waits had similarly high praise for Primus. "Those guys are great," Waits said. "I bought a fish off of them. I'd been fishing for three days. I hadn't caught a damn thing. They were going by in the next boat, and I bought a barracuda off of them for six bucks and put it on my line so I could bring it home, so I didn't have to stop at the market -- the humiliation of that."

Anchored by Claypool's energetic bass playing and cartoony vocals, Primus began their recording career with the 1990 live album Suck on This. The 1993 Pork Soda featured their biggest radio hit to date, "My Name Is Mud" (RealAudio excerpt).

Last year the group released Rhinoplasty, an EP that included revamped versions of songs by Metallica, Peter Gabriel, XTC and others.

(Correspondent Richard B. Simon contributed to this report.)